There's two possible issues that I can think of. Both are easy fixes.
Firstly, maybe your domain name hasn't propegated to point to your hosting server yet. This is normally pretty fast (30-60 minutes) but in some cases it can take 48 hours (sometimes even longer). If that's the case you'll just need to do a bit of waiting. Be patient and it will update.
If the holding page is the one from your hosting company then you will need to go onto your hosting server using FTP (or a file manager if your control panel offers that). When you get to the main www root of your site (normally a folder called 'public_html' or 'www' or something like that) you'll find a file called index.html or index.htm as well as index.php from WordPress. When you find that delete any index.html file and leave only the index.php file. When there's an index.html file the server will look for that before the index.php file, so the home page of your WordPress site won't get found while that file is still there.