...Also, I have not calibrated my monitor yet. Is there a free software that you can recommend ? ...
There is no software, on its own, that can calibrate your monitor accurately.
You will need a puck that actually measures colours emitted from your monitor.
This puck will actually be placed on your monitor screen when you calibrate.
In conjunction with software this actually allows accurate measurement of the colour and luminance that your monitor actually projects and also allows accurate alterations to be made.
Xrite and Datacolour are the two tradenames you will need to investigate.
BTW I read Cletus' post and I heartily endorse the sage wisdom expressed there.
If you are going to make a real go at printing then you will need to get to know every aspect of colour management and softproofing otherwise the results you get will be pretty random and low quality.
I note a complaint already that your prints are too dark - this is a classic problem for newbies and is usually due to monitor luminance (brightness for the uninitiated but luminance is the correct term) being much too high.
In addition, many consumer-level monitors have real issues getting to a luminance appropriate for image (and video) editing which is usually well below 100 cd/m2 because the entire selling point of those monitors is a bright display.
The good news is that the whole learning process is doable - I learnt the entire workflow from scratch a few years ago.
Tony Jay