How do I add new Tilesets?

I been using Essentials for awhile now, mainly for my custom Trainer battle videos, but the only thing that is off is that I use mostly Gen IV/V sprites, both OW and battle, and they just look to out of place with all the Gen III tilesets.

I was wondering how can I easily change the outside Tilesets with better ones, like ones from Gen IV, because I finding it a bit difficult to add tilesets that other users make for RPG Maker XP for Essentials, and can't seem to get everything in the right size that would fit the tileset that is used in Essentials?

1. Click the material base button.
2. Click the GRaphics/Tileset Tab
3. Click Import, and the select the tileset file you've got in your documents.
And it's done.