The forum and your THS membership are separate and those outside TrustedHousesitters can also access the forum page. Dates are posted on your membership page where potential sitters are actively searching and apply from there as well.
A suggestion I have would be to link your member profile to your forum profile so members an easily pull up your profile. To do so, click here How to add a listing or profile link to your FORUM profile - Owner & Sitter Exchange - TrustedHousesitters Community Forum