You're stuck on an island with a cow and you're starting to get really hungry...

The Player

You play as this orange shirted* guy; the camera follows the middle of him and your mouse.

*or is he just really sunburned?

Picking up Sticks and Stones

You pick up sticks, stones, and your tools by walking over them.

Crafting

Pressing (X) will open the crafting menu, where you can click on an item on the left side of the screen to craft with the materials you've picked up.

Spear Tossing

While you have the spear, holding the mouse button will start a "swing aim". Let go to have the spear fly in the direction the yellow line is pointing. Once your spear lands, it will be able to be picked up again by walking over it

Equipment

You can only carry one tool at a time, pressing (O) will drop your currently held one allowing you to pick the other up.