seems that you are using the command line version of decred you could try the version with Decredition for a less challenging experience

anyway for the dcrctl a batch file is the solution, create a .txt past insied the code below and rename it to .bat
dcrctl.exe
cmdk
Thank you! Decredition is much easier

But I have 2 more questions:
Am I right that I need enough DCR to buy a whole ticket which is about 71 DCR right now?
Which pool is recommendable? Or isnt there much of a difference?
Yes, you need to buy an entire ticket to stake it.
Check here for current ticket price:
https://dcrstats.com/ It also lists a number of stake pools you can look into. I can recommend stakepool.dcrstats; have had 0 issues, and the android app is nice.