See if your local church supports mission work. The larger the church, the more chance they do.
There are missions that focus on spreading the gospel. But there are also ones the focus on building something or providing a service.
How do expenses work? In many cases, you ask others to help finance your trip. You divide up the expense into smaller amounts and ask family members or other church members to help cover the cost.
What do you get out of it? You get to travel to another country and see what it’s like. You learn how to work on a project with others. The church may have done this before and has a preparation class to educate you.