my 1986 firebird has an ongoing issue with blowing my gauges fuse every time I decide to get on the gas pedal a bit, at first it would simply just blow the fuses but now the speedometer is not working at all and all other gauges are working just fine. The speedometer does in fact work whenever I use my brakes, I'm not quite sure what to do because I'm quite inexperience with wiring and electrical

id also like to mention that I have a double din aftermarket radio but I've had that installed for more than a year now and I've never had problems until now

 

Welcome to TGO,
There's really only condictions that will cause a fuse to blow, a short in the circuit or another electrical component wired into the circuit that's causing excessive current draw. You said the stereo's been in for a year so it's probably not that, are there any other aftermarket electrical components installed, it's more than likely a short.

The search function on this webite will be your best tool to diagnose issues with your car, Do a search for gauge fuse and a ton a threads pop up with your exact same problem. One poster claimed that he pulled his fuse block down and found a wire with exposed wire strains shorting to the next terminal. It appears that there are a few different circuits powered by the GAGES fuse

1986 Firebird gauges fuse issues. - Third Generation F-Body Message Boards
"I figured out the issue I do believe. After removing the immobilizer ( which was terribly wired and needed to be removed.) I tested again and blew yet another fuse. Then I ripped out my head unit for the 3rd time. Discovered 2 RCA cables that were uncovered and decided to make sure they were free and not touching anything . Then sure enough I turned the key and put in a new fuse. And all was good."

The link below is a great resource to reference from for the 82-92 F-Body
AustinThirdGen.Org (archive.org)