how do i stop my lighting fuse from blowing?

i fitted a new light fitting in my kitchen and it blew the downstairs lighting fuse in the house fuse box. I changed the fuse and checked the wiring in the new fitting, switched the electric on, and again the fuse blew. all other areas of the house have power,except the downstairs lighting. the fuse box is a memera box, which has separate fuses for the power in the house.the fuse that blows is a 5amp. any help gratefully received. thanks.

david
April 2010