That was preeeetty bad. But hey, nobody comes up with anything good when they're starting out.
I'd give you some advice, but my best recommendation is to leave these tracks for a bit, listen to some really good mashups, compare, and then look at what you need to improve.
Keep at it, and you'll be putting out sick mixes and mashups some day. But whatever you do, don't give up because of initial difficulty. Music is a super hard thing to do, I've been playing piano for 12 years, and most of the beats and stuff I make sound like complete shit. Just takes time.