Can I share Internet access from PC to Phone?

It depends on the phone you have (assuming your question means that you want to use your PC's existing Internet connection - ADSL or whatever - from your phone).

With Eseries models (E50, E60, E61, E70) and the 9500, 9300, 9300i you could use the, so called "IP passthrough" feature with the USB cable (requires a Windows PC with the Nokia Network Bridge from http://forum.nokia.com/ to be installed).

With all models that have WLAN/WiFi (and with WLAN also on your PC), you can configure your PC as a WLAN router/access point, or use an ad hoc connection.

And with all Symbian phones untill 6600, is direct, like that: http://www.russellbeattie.com/notebook/1001649.html;

With the phones after 6600, is with Gnubox project.