From the author's README on Thunderstore

Winaar Shirt

A shirt based off an inside joke from the ReSkate Discord.

In game

In the shirts.

Credits

Shirt by Woozy. PNG by IV on the ReSkate Discord. We're so proud of you, HashbrownCat!!!

Install I Need Help With Winaar Shirt

You need ReSkate and your own copy of skate. on Steam.

Open ReSkateLauncher.exe and go to MODS.
Search for I Need Help With Winaar Shirt and click install. The launcher also installs anything it depends on.
Press PLAY. In game, the MODS tab of the ReSkate menu (Insert) turns it on and off.

Or install it by hand: download the .zip and drop it on the launcher window, or unzip it into its own folder in Mods\ beside Skate.exe.

Maps show up in the ReSkate menu's level list. To join a server running a custom map, you need the same map installed. If the game won't load after installing, see known issues.

skatemods doesn't host or review this mod. The download comes straight from Thunderstore. Only install mods you trust, because scripts can run code.