You need some sort of statistics reporting. Quite often this is provided as an extra option from your hosting provider. There are also third party options such as those offered at
extreme-dm.com or
statcounter.com - these generally involve adding javascript code and a small image to your pages. These in turn, link back to the remote site which monitors your site visitors (including SE bots).
FYI: here are a few links to previous discussions on Web stats packages / log analysers:
Which Web Stats do you use?
stats tools
Web Analytics
Hope that helps,
Paul