…unless you actually want to buy something from them. Here are two very common things that you should not send messages to sellers about:
Asking them to “send you work” or buy your gig. Sending unsolicited messages promoting your services is considered spam and can get your account banned quickly. Don’t do it.
Asking for general advice on how to get started. There is plenty of information to get you started at the Seller Help Center: https://sellers.fiverr.com/en/ and if you have questions, the forum or customer service are better places to ask for help.
Also, if you haven’t done so, it’s also very advisable to read the terms of service ASAP.
Some research and persistence go a long way. Good luck, new sellers!