ok so i got 2 problems, i built a new pc and it has no OS yet, so i put my old hdd to my new pc because it needed one, and i ran the disk to install ubuntu but it says that i only have 3gbs left and it needs 4.9, i have more than 3gbs (500gbs to be exact) and im running ubuntu on the try it out mode, i need help on this

the second one is my destop dosent fit my screen i have no idea how to fix it.