You need to buy / lease planes, then rent gates, and establish routes.
If you make a profit, you will have positive "DOP", which is ticket revenue - flight costs.
You cash would change according to your DOP every hour (which is a game day). For every day (which is a game month), leases, gate rents, maintenance... etc. would be debited from your cash, which would also affect your cash level.
As for value, basically whenever you have income, your value rises accordingly. Go buy planes that cost less than they are worth would also increase your value. Depreciation would decrease your airline value though, so keep your profit higher than the depreciation would be the way to go for a higher value.
