Hi TK0613,
Congrats on your new Sunny!

Your floor plan is a popular one.
You appear to have issues with your slide system, which cannot extend or retract from the camper. When your year 2000 camper was made, Sunline used at least two brands of slide drive systems: a Barker slide drive and a Dewald slide drive. I cannot say which brand you have, and you may not know yet either, but we can try to help get you going. You may have to post some pictures of things when we get to that stage, so we can see what you have to help better. A prior owner may have modified something from the original, and by seeing what you have, we can get back to what some of the issues may be.
Let's start with the big picture on how the slide drive system gets its power to run the motor.
The slide drive motor is a 12 VDC reversing motor. Due to the heavy power draw of the motor, Sunline would create a separate power circuit direct from the camper battery. The battery is up by the LP gas tank on the trailer tongue and is charged by an onboard power converter "when" the camper is plugged into 120 VAC using the shore power cord. The power converter panel also has 12 volt DC fuses for the DC circuits inside the camper, but not for the slide drive system and 120 VAC circuit breakers inside it.
As Roger stated, your camper should have a wooden junction box with a screwed on wood cover that houses a bunch of connections from the battery, the slide motor drive and the truck 7 wire cable. There are also some fuses in there and an auto-resetting circuit breaker. It is most likely on the front cargo area under the front bedroom floor. Look on the camper's left side (driver side) in the front cargo area for that box.
Here is a picture of what is inside a camper of your era, yours may or may not look like this, but the box with the cover off would be similar.
Please locate that box, remove the cover, and photograph the inside so we can see what you have. That black cube with the four wire posts on it is part of a Dewald slide drive.
We're trying to figure out what you have, and you'll need to know about this box anyway for the future.
These two posts have pictures of the Dewald system. If yours is the Barker system, we need to see the slide drive motor under the camper.
https://www.sunlineclub.com/forums/f63/right-slide-motor-19581.html
https://www.sunlineclub.com/forums/f73/t260sr-slide-18935.html#post146151
Now, for the big picture, the battery and/or the onboard power converter provide/create the 12 VDC power to operate the slide. Please tell us if you are plugged into shore power? Do you have a working, fully charged 12 VDC battery on the camper? Do any of the lights inside the camper work? The lights are all 12 VDC, and it helps to know whether they work.
"Some" of the older campers did have a slide drive kill switch that would kill power to the slide drive system. My 2004 camper has one, but I'm unsure if yours does. The 2005 to 2007 Sunlines may not have this switch. You can look for something I will describe, you have a large toggle switch on the wall inside the camper, on your floor plan, maybe it is by the rear entry door. That switch, spring returns to the center when you let go of the button. You press the switch for extend and when you take your finger off the button, the spring returns to the center. Or press to retract and let go and it springs back to center. That is the main slide switch located in the open on a wall or cabinet side, which you press to extend and retract the slide. The slide kill switch will be an on/off switch, a maintained switch, no spring action. This kill switch is usually out of sight in a top cabinet. This only gets turned off for emergencies to shut the motor down or to prevent someone from running the slide in or out. Look to see if yours has a kill switch, it might be turned off.
We are unsure of the next steps to help you because we need your feedback on the above questions. In case this happens, do you have a volt meter that can read DC power or a 12 volt DC test light and know how to use either? We may have to troubleshoot why the slide motor is not moving. If you are unfamiliar with using those electrical tools, do you have a buddy who works on cars? They should have them and can help.
Another question: Did the prior owner have the slide out for you before you bought it and they retracted it? Or has the slide been closed for many months or years, and now you have it? If the slide has not been opened in a long time, it may be stuck mechanically, and the motor does not have enough power to free it. The motor might grunt but may not move. Or the motor may not make only a very faint sound when the slide is stuck.
I hope this gets you started.
John