This following steps will set your sdk to your eclipse. 

--> after downloading open eclipse, 

--> go to windows menu

--> select preferences

--> select Android tab

--> click browse button and select path of sdk folder and click apply.

  Following steps will set your emulator on your pc, which will act just like your android device.

--> go to windows menu

--> select Android Virtual Device Manager

--> by default list will show nothing , you have to create new one. So click CREATE button , it will open one dialogue box fill name of device(which can be anything you want)

--> choose your device (any)

--> target your sdk version (e.g 4.1,4.2)

--> select CPU as ARM

--> click ok  

 It will show your AVD list which you have just created. 

select your AVD and click START button, your avd will run in sometime, wait for that till it doesn't look like your android device.