Fill in basic information to open an DSP account linked to your APX account.
2.1.After opening DSP account, you can transfer your APX balance to your DSP account by clicking the highlighted button "Transfer Balance to DSP!"
Transfer amount should be N*$100, N>=3.(i.e. $300,$400,$500...)
2.2 You can also top up your DSP account directly：see more at payment-method.