I need help on recording first MIX into multitrack program, (pro-tools,behringer uca222)

You will indeed need an external soundcard, not only for recording but also for using Serato and Pro-Tools. I’m not an expert on this stuff, but I use an NI Audio 8 myself. The Audio 2 is NIs most simple soundcard, but is way more expensive then a Behringer (http://www.native-instruments.com/#/en/products/dj/traktor-audio-2/). If you want to record stuff more often it’s a good thing to invest in a proper soundcard that you can use for the next couple of years!