Can I make my own Internet network using WLAN?

I'm going on holiday, and on holiday we have a usb dongle that allows a laptop to connect to the Internet. Is there anyway that I can use the dongle and create a network that my iPhone and ipad can connect to? I have no idea, but I thought WLAN might have something to do with it?

Yes. Probably.
You need to make an ad-hoc Wi-Fi network. That's part of the Wi-Fi spec so I presume the dongle supports it. The operating system should have tools to set it up.

I've done that on Linux, to copy stuff to/from my tablet. My laptop actually boots up to ad-hoc if it can't find an access point. I can't remember exactly what I did now, but I have some entries in my hosts file so I can login to the tablet by name.

You have internet, have modem. Buy wireless router, set it up and you get Wi-Fi at home.