Tina,
There are 3 'ball joint' linkages in the wiper system - a central one and then one for each wiper arm. Sounds like the link for your driver-side wiper is the one which has come off which is good as access is easy once you have removed the big plastic cover under the bonnet. The clip that Paul has linked to you will sort out the immediate issue but for the longer term you should consider replacing the whole linkage either with the MG Rover fix available widely via eBay or one of the after market ones. I fitted a Mike Satur replacement which works well but needs quite a bit of fettling to fit. Some useful stuff here:
http://www.the-t-bar.com/en/forum/9-mgftf-pitstop/33878-wiper-motor-a-linkage-replacement-how-to#33881
Richard
1.8i Mk2 Solar Red, 16 inch square spoke wheels, MGFMania hood with zip-in glass rear window, DRLs, Kmaps ECU, Pipercross panel air filter, MGOC Supersports back box & some cockpit bling