Please clarify what you mean/are asking?
If I gather correctly, You have PC #1, with an Operating System running OBS, and it is sending a stream to another venue (/platform)
Did I get that right?
Now what do you mean by can you use OBS at same time?
- Sorry, you are using OBS to stream
Are you wanting to run a second instance of OBS to do something else?
Or are you trying to stream from OBS a demonstration/tutorial or similar about OBS? [this would naturally require a second instance (possibly a 2nd PC)
or ??