Novice and wiring

[4thgencreamsicle]

I am a complete novice and am dealing with a fuse that blows every time we get the rig to turn over.
It’s a ‘69 c10 that was my great grandpa’s. I am determined to get this truck running. It’s original engine was at some point replaced with a ‘73 crate engine.

My hubby is a truck guy, currently working on his own rig. He’s happy to help me but I’d like to do most of the wrench turning on my own.

It’s a 20A fuse that comes off the battery cable. I will attempt to attach a pic, kinda awkward to do on my iPad. Hopefully it works.