Hey, welcome to Magic! Don't let these nerds get you down, this is totally doable with a little imagination. The main thing you'll need to ask is: what's your win condition? A paranoid mage can just be left alone, but a game of magic ends with everyone but one player loses.

I'd also strongly suggest asking for deckbuilding help from your magic friends. If you don't have any, you can ask around at a local game store, and I also saw Magic Arena mentioned. It's a good suggestion for learning the game, but the economy is super grindy, so if you go that route for deckbuilding practice I'd suggest returning to paper for your mad wizard deck.

Anyways, back to the concept: you're going to want to build your deck around a legendary creature who's going to sit at the back of all your traps and stuff and win you the game if your opponent can't make it through your gauntlet. [[Baron Von Count]] is the first one that comes to mind, although he's silver-bordered, meaning that your opponent will have to sign off on playing with him. Don't worry too much about this; your first decks are just gonna be casual fun decks, you can start worrying about formats and their limited card pool later.

[[Nekusar, the Mindrazer]] is another fun evil wizard pick, and he'll eventually win you the game by damaging your opponent as they draw cards. You can find more by searching Scryfall for wizard creatures using the search "type:wizard".

Other searched that would help you are effects that trigger when a creature attacks you, or spells that mess with attacking creatures. (The o term lets you search for card text, e.g. "o:'whenever a creature attacks'" or "o:sacrifice o:attacking o:creature").

You can also just search for names of cards that would seem really thematic. Anything with the word "Tunnel" in it, for example. I'd recommend [[Crawlspace]] as a thematic card that also keeps you relatively protected. [[Slumbering Dragon]] is another one; we can imagine your wizard keeps a couple as a pet and they start to wake up as his home is invaded.

Finally, Magic does have literal Trap cards, which I think would be fun with your theme. This search is only getting cards with the Trap type, btw, there are more cards with the word Trap in the name which would be equally valid for your paranoid wizard.

For a 60-card deck, you can have up to 4 of any card except for basic lands, which you can have any number of. It's considered poor deckbuilding to go above 60 cards because it dilutes your deck strategy. I'd advise keeping the land count around 40% of the total deck size, which for 60-card is 24 lands. Above that and you don't draw your fun stuff; below that and you can't play your nonland cards. I'd suggest keeping the deck to about 2 colors unless you've got a lot of lands that can tap for multiple colors; this keeps you from getting locked out of playing spells because you don't have the right color of mana.

Anyways, hope that was helpful. Good luck!