Is she attempting to connect to your web server on an internal network (like, in the same office) or is this from another network (she's across town or in another state)? That's important information. You say "colleague" which implies that she is in the same office... but you aren't very clear on that.
Have you forwarded port 80 traffic in your router to the computer that is running the web server? This is an important step if your colleague is not on the same IP subnet as you are. Your router would need to know what to do with those incoming requests for information. So, if you forgot to do that... meaning you forgot to go into your router and handle the port forwarding, that's something that needs to be done. Also, consider putting the web server computer on a static Internal IP address in the DHCP reservation table. That way, you just forward to one IP address, and you don't ever have to worry about changing that later.
Does your router have a firewall as well? Again, this is something that needs to be expressed in your question, as to whether you have addressed it already, or you didn't even know it was there.
Does your ISP allow you to host a web server on the connection plan you are currently paying for (don't be surprised if they don't, they want to charge money for everything they can)? You might have to change the port you are hosting the web server on, if your ISP blocks traffic on port 80. You might have to use a non-standard port of 81, or 8080 or something else, which would require you to set up some NAT table, or have this different port forwarded through the router and have your colleague always append a :81 or :8080 to the end of the IP address she attempts to connect to. Just as an example, Cox home service in New England blocks port 80 traffic like this, so people can't host their own web servers at home without having to do something like this.
So... is there something you can do to get this to work? Most certainly. Of course, we need to know what you have done so far, and we need to know what you are working with so we can tell you what more you can do.