You can check your bandwidth from https://steemd.com/@thedesertartist
Instead of doing all your activity in one go it is suggested to spread it across so that you always have some bandwidth for you actions. You can buy steem from any exchange (Eg:Bittrex or Binance) and then move to your account. Once you have your steem you can convert it to Steempower. For details check out https://steemit.com/steem/@steemladder/how-and-why-to-power-up-on-steem