WEEPING WILLOW TYPE TREE IN THE GARDEN?????

It's hard to say, without seeing the leaves, what kind of tree it is. Do you have a picture of it with leaves??
It could be a type of maple...some laceleaf ones can be this shape. Or it could be a weeping birch....I've seen those too.
I would say prune it in late fall or early spring.

It coulld well be a willow. Trouble is that if it is a willow then pruning should be done AFTER the catkins have finished. They appear on wood grown in Summer.Other trees as said may be pruned in spring.

yes i agree with Gilli, it is very hard to tell without any thing else to go on. there are lots of different types of willow, i have 2 that have red stems through the winter, so i don't think it is either of the two i have, but there are quite a few other dwarf weeping varieties, another i would saggest would be a dwarf ornimental cherry tree, i had one a few years back, that had just the same shape, was approx 4-5ft tall, and flowered pink early spring, but never fruited. this i pruned late autumn, but as owdboggy has said if it is a willow, best leave it till after the catkins. if it is a maple as Gilli has saggested it needs to be pruned while dormant, before the sap starts to rize, so to be able to give good advice we do need a bit more to go on please.

Looks like Salix 'caprea Kilmarnock', the Kilmarnock willow. http://www.jprwillow.co.uk/salix_caprea_pendula.htm
takes you through the pruning of this.