Press space to jump. Just space OK? And avoid the bad things such as birds and trees. It will be harder and harder every few moments. And there is daylight cycle so don't worry when it gets dark.
I got this from the internet when i don't have internet. It's the dinosaur game that i played and it's fun! I want to thank the youtuber that taught me how to jump smoothly and thank the creator of that game whoever it is.