How do I add money to Coinomi?

Can you guide me through the process of adding funds to my Coinomi wallet? I'm a bit unsure of the steps involved and would appreciate a clear and concise explanation. Is there a specific method for depositing money, or does it vary depending on the type of cryptocurrency I'm looking to purchase? Also, are there any fees associated with the process, and if so, how are they calculated? I'd like to ensure I'm making an informed decision and understand the entire process from start to finish.