Simple garage conversion help

[harveyyoyo]

I have done lots of reading and searching but I would still like to get suggestions on how to convert my garage to a mini office/man cave extra room. Right now its what i think is a nice structure but damn ugly. I dont park my car there anyways and I my house is small so having this place to hang out just makes sense. Dont have the money or any other help right now so id like to do this as cheaply and easily as possible. A few pointers.
Right now there is a terrible smell from animals using it as a hideout. What would be the best way to get rid of that smell?
Because animals try and enter I would like to work on the door first. I need something that cant be left open ever. As you can see in the picture I have another part of the garage with a proper door but I wasn't planing on fixing up that part. I was going to leave that as is for storage and just convert the main part. What do you think?
Can I use the wood thats from old shelving as a frame for the new sheet-rock (if thats what I go with)? Are there better ways to build a frame?
What tools do I need to buy for this job?

Here are the pictures. All ideas and comments are welcome. Links to videos of guides I can follow would be great as well.

 

[Hot Rod Grampa]

Looks like you will be buying a whole lotta tools and learning a whole lotta skills. Being you have a concrete block structure you will need to fir out the walls with wood so you can insulate then cover with Sheetrock or whatever. You will need to run wires, outlets, lights, switches, as well as learning to frame the garage door opening so it too can be insulated and finished. Start reading and watching some videos, but don't buy over the top tools. Most of what you will be doing can be done with a good cordless saw, drill and screw gun. The big expense will be an sds to make drilling the block easy. Then basic pliers, strippers and screwdrivers for electric and some sparkling tools. Have fun!

 

[MrBalll]

Are you totally opposed to getting rid of your garage door?
Seems like it could be nice to lift it up on a summer night and just relax. Could probably find some used garage pieces on craigslist or online somewhere. This could save you a good bit since you won't have to frame and insulate an entirely new wall.

For the smell you just need to clean all the floor and find the old excrement and rotting bodies of the animals left behind. Clean all that and it should help immensely.