[Longing for help] Scary threatening of booting my PC D:

[TinyBuilder]

I'm so scared right now. So today morning i was doing some cool stuff and suddenly when I seen my screen, a windows error message came saying not to screenshot the screen, and asked me to open a notepad. After few minutes, i seen a chat box asking me to give him/her fresh dinos or habbo coins. Or he/she will fuck my PC up D: I'm really confused what type of PC controlling is this. i'm so scary too I didn't yet meet him again, can anyone give me some suggestion what to do?

thanks D: 
Sorry if this is a wrong section :L

 

[Wassim]

your a rat victim, everything you write or do is recorded and send to there computer

 

[SkeetEmUp]

Laffs. Ratted.

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[Macemore]

Reinstall windows. Try getting linux too

 

[ButtLord420]

Use some of the links skeetemup provided. Plus youc an use AVG free edition. Also, check if you opened any files recently that may of had a strange action ie: not opening or dosen't do anything.