Hi Linda,
If you mean the shopping centre with IKEA then take a look at http://www.ikea.es/murcia - you need to head up the motorway towards Murcia. When you get near Murcia the junction numbers suddenly switch to 7xx which can be a little confusing but basically come off at exit 763 and bear right down the dual carriageway until you hit a roundabout/junction with lights where it crosses over a tramway - turn left here then left at next roundabout and follow the obvious way into the huge car park.
If you come off before 763 then you'll do what we did and drive round for ages trying to get back on the motorway !
There's another part of the complex a few roundabouts further on (I think you go straight ahead at the 2nd roundabout instead of left and you should see it) - it includes Leroy Merlin for example.
Good luck !
Dave & Ailsa, 2A