unless you already have a visa for a domestic helper, you need to get a letter from your husband's sponsor with is salary details, upply to immigration for a permit and specify the nationality you want.

Once you have the visa approval, you go to the agency, browse through the CVs they have, pick one, hand them the approval document, copies of passport of your husband ...etc, pay the fee and they take care of the rest

Nothing is guranteed in terms of quality of CVs, so do not put much hope on that, if you are lucky you will get some one serious who would like to work

You may get lucky and find one already here and returned by her sponsor for some reason, you can take her on loan, try her and if she is good transfer her sponsor .. but again nothing guranteed

Good luck

"The best way to predict the future is to create it".