Yesterday I installed my new Ubuntu - wow! Ubuntu is a very cool. Today I want to work ob my project, but I become following error:

I already found a solution: How to fix "The system is running in low-graphics mode" error?
I started the virtual terminal with Ctrl + Alt + F1 ...
How can I log in now in the virtual terminal?
I must install a Nvidia-Driver.
Greets
Sorry for my not so good english - I'm in the 6th grade