First of all check can you use SSL with your current hosting solutions(you will have to ask your hosting company for this). If you are using dedicated server or virtual private server this should not be a problem. But if you are using shared hosting you will need an IP based one to use SSL. Just ask your hosting provider.
Second of all use the SSL only where necessary, you do not need it on all pages(only for those with the sensitive data). Then choose a SSL certificate provider (GoDaddy, VerySign, Comodo etc.). They will have to check your company, make some phone calls etc. to prove that your business is not a fake and then they will issue you a certificate that your hosting provider will have to install for your website.
Hope this helps )