Welcome to forum. Questions are welcome and answered. No question to dumb, We've all been there.
As to your question, Definitely butyl tape. It don't dry out like putty tape, remains pliable for years. . It's very important to seal corners very well. Corners are a prime area for leakage. Butyl is inexpensive, available on line or an rv dealer. I always keep a roll in my trailer
Jim and DW
2001 T-2553 Sunline Solaris
2006 GMC Sierra Duramax 2500HD 4X4
Firestone Transforce AT tires
Reese Dual Cam Sway Control