Jack the car up & put on axle stands; remove the wheel, and then place the jack under the wishbone & jack it up til the drop link feels loose, i.e. is neither under tension nor compression. Undo the nut holding it on at each end, and remove. The threaded part will probably be covered in dirt & crud & everything will twist when you try to undo the nut - secret is to insert a 17mm spanner behind the joint to grip it & stop it spinning. Once removed, put the new one in, release the jack, then put the wheel back on, jack the car up & remove the axle stand. Same goes for the other side. That'll cost you under £40, and only needs basic tools. If you need any more help, post on here and help is at hand