Hey guys, I’m extremely new to programs and software such as this and when i say new, i mean i’ve never done it before lol.
I’ve taken 2-3 days to watch videos on UE4 and so far i understand the basics of building a level, lighting, rendering, props, coloring, even height maps if needed. (for a TD game i don’t see me needing that one)
But there is so much I don’t understand and i can’t seem to find stuff about it. Should i start blank template, third person, or top down base?
Many other things such as getting stuff to work within the game, spawning, waves, upgrades, the entire thing. I know i’m asking alot here, but can someone help a noob?
If you go into the UE4 launcher, there is a tower defense example game. It is named “Strategy Game” and is located under the “Learn” tab, in the “Example Game Projects” section. It can get you pointed in the right direction. I hope that helps!
Make sure to take a look at those links 
https://docs.unrealengine/latest/INT/Resources/SampleGames/StrategyGame/index.html
https://docs.unrealengine/latest/INT/Search/index.html?q=tower+defense&x=0&y=0 (here you can find many useful information about how to create a tower defense game)
Also make sure to ask specific questions here in the forum -> we are always here to help 
What kind of tower defense game do you want to make? I always start blank project and implement my own stuff for the game.
Have a look at my Tower Defense Template here:
https://forums.unrealengine/unreal-engine/marketplace/1667541-tower-defense-template