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It works like this and feel free to ask again as it is complex. Every day new steem is generated (inflation of 9% per year) and this becomes largely available to all to make upvotes. Thi sis called the rewards pool. Each person can upvote on others not costing you anything. People with a lot of steem power (see the wallet for this) get a larger part meaning their vote is worth more. There is a limit to the number of upvotes you can give each day. For now say you can do ten votes and then recover and do the same again after 24 hours.

As for putting money in yourself it means you put steem in your account and with that increase your steem power (called power up) which makes you a person with a hiher vote value. Otherwise it takes so long. If you get votes from others the rewards come to you after 7 days (see wallet) and you claim them meaning your steem and steempower get a boost (or a little boost).

For now this is enough I think.