There are many ways you can make a contact with other Partyaner users:
Submitting a message request is the most common way to contact other users. If you just need to ask some information you can submit a message request via profiles. Then other user receives your message request and accepts or rejects your message request. If user accepts your messsage request then you make a conversation and your message goes to inbox (messages).
If you want to join to some Music Band / Group then you can submit a membership request via the Music Band / Group's profile. Then other user receives your membership request and accepts or rejects your membership request. If user accepts your membership request then you (your profile) will become a member of that Music Band / Group.
Submitting a managing request to profiles you want to manage is a great feature if you want to grow your business. First you need to have a Manager / Agency profile to do that. If you don't have a Manager / Agency profile you can create one. After you choose by which manager profile you want to managing other profile, other user can accept or reject your managing request. If the user accepts your managing request then you become a manager of that profile and all inquries will go to you if someone choose your manager profile to contact because one profile can have more than one manager.
Last type of making contact with Partyaner user is via Ads on newsfeed or directly on user's profile in "Ads" menu. It's a button called "I'm interested" which means that you're interested in the user's Ad so you can write a short message and wait for response. Also, in this case the other user can accept or reject your message request. If user accepts your messsage request then you make a conversations and your message goes to inbox (messages).
Read How should I know what language should I use to communicate with another user for more information.