first, go to hsbc.com.hk (you don't need to log on at this moment)
and at the left hand side, click on the 3rd one - Investment, then again
and at the left hand side, click on the 3rd one - IPO
and look at your right hand side, if there is any IPO which can apply via them, then you will see that listed on the IPO Listing, then you will see there is and 'info'/'apply' button next to that security/stock name, then you click on it, then just follow the instruction (practically just click and select of the Terms and Conditions), then you will see they ask you to log on, so, now, you log on and then process the remaining procedure, such as choosing the number of shares and account to be debit for the funds and as well, whether you would like to process a loan for such application - if you use an integrated account, i.e. Premier/PowerVantage/SmartSavings are offering IPO loan
so, that's pretty much it, just follow their instructions carefully from after you log on.