Welcome to the forum!
 
Before you can be creative you simply need to read the manual and do the tutorials.
It's not very practical that we start copy pasting the manual here, is it? :o)
When you have done the homework and have specific questions, you'll find help here for sure.
 
And whenever you ask, it's good to list your gear and software specs. Put them in your signature/footer. Then spend a moment formulating your question.
Now, for example, we don't know what software  version you are using, nor what's the mic you mention (laptops own mic, external mic connected to external soundcard???). Neither do we know how you've set your track inputs etc., i.e. how have you tried to solve the problem.

I forgot to mention I don't wanna use any external instruments either, no MIDI 

Yeah.... kind of...
 
Music Creator  records only 2 things. Audio and midi.  Audio is from the mic which you said you don't want to use, so that leaves midi. Midi is totally digital and can use SI-Strings as well as dozens of other synths.
 
Midi can be recorded a number of ways. The most common is to have a dedicated sound card or interface which accepts midi input or a midi keyboard which has a USB connection to the computer. Either works fine. You select the midi source from the midi inputs drop down and select it.
 
If playing a keyboard is not your thing, there is one other way... maybe 2, but similar. 
 
One is to import midi loops and string them together and edit them as needed.
 
The second way, albeit the hardest way to work with midi is to use either the PRV or the staff view and manually click the notes in one at a time. You have to place each note, determine the pitch, the duration, the velocity, and any controllers for that note.... all of which takes time...lots of time.
 
I have heard several songs composed through the years on this forum where the poster said this was exactly how they did the composition. So it's not impossible to do.
 
If you don't play a musical instrument, I would suggest looking at the loops and possibly even Song Smith from microsoft >>>> http://research.microsoft.com/en-us/um/redmond/projects/songsmith/   this allows you to make music without having instruments. Some genre's are more easily made than others. Then import the tracks into MC and mix them as you need.
 
That would be my suggestion to you.