Yes, you could use PaintDotNet, Gimp is also cool - but not as versatile and lightweight.
A hint - when you’re done with pixelarting, search for IrfanView’s thumbnail viewer (it’s packed with the app) and look for the feature called Create Contact Sheet within the File menu; it could serve you well for creating various tilesets because it lets you define the size of both the image (all the standard formats, PNG being one amongst many) and tiles, number of rows, columns and a few more.
For example, you can pick a few (or a dozen) tiles you’re dubious about and share it via some image host on this board - you only have to pick them from your folder and create a contact sheet. You can even enlarge them if that’s your preference.
In fact, IrfanView’s really neat when it comes to manipulating anything pixeled. I’m sure there are plugins that take part in even more easement, if you have a great heap of really small images. It’s free.