Im just wondering how do i get a house carl to stay at my house while i have lydia as my steward?

Which house? The Jarl only gives you one housecarl, when you become Thane. Since you have the land, you need only do the help the people quests to get a housecarl for any Hearthfire house.

Lakeview manor....i had lydia follow me from whiterun then made her a steward but i thought i read that you can have both a steward and housecarl live at the manor and im having a hard time doing this and was wondering what i have to do to accomplish this?

I do have the woman from the bannered mare (the unbroken) waiting in front of the manor outside to help booster the defense of the manor...would this do something bad?

The usual tasks, pick and sell vegies, chop wood, help someone in need, or do some deliveries, you only need to help three people in the hold.

If you are struggling, you can also have a follower with you, a non human follower and a horse. You can also get the steward to buy a horse for the stable. Your spouse and your children can occasionally help out with fighting, and even the Lakeview Bard has been known to join in, but you will need to pickpocket a decent weapon onto him if you want him to be much help. You can give the children daggers or wooden swords.

If you aren't thane, you will not have a housecarl. To become thane, speak to the jarl. You already own the land, so he'll tell you that you have to become known throughout the hold to become thane. Then just help out 3 people in the ways aussie outlined above, and go back to the jarl. He should then assign you a housecarl.

I've never run into trouble I couldn't handle at my home, but then, my character hasn't advanced the MQ, so I don't have dragons flying around in my game. Still, between your housecarl, steward, follower and yourself, you should be pretty well covered. Even moreso if you marry a follower like Jordis or Aela and leave them at home; they will also fight for you.

this and u should be good 2 go,but if u leave uthegard there 2 long she will return 2 whiterun

Im gonna do the missions in falkreath and when i get a housecarl how do i get her to go to lakeview manor?

Your housecarl will find her own way to the house.