An A1181 can be a number of older MacBook models. Depending on its exact model designation, you may be able to upgrade it to OS X 10.7 "Lion".
Doing that will require a bit of effort on your part. First, you will need to upgrade your current OS 10.4.11 "Tiger" to OS X 10.6.8 "Snow Leopard", after which you can download and install Lion by following this link: Mac OS X Lion Installer.
Getting that Snow Leopard installation disc is likely to be the hard part. Apple no longer sells them, but aftermarket sources exist. Legitimate aftermarket sources will sell an unopened white box that looks like this:
Accept no substitute. There are no legitimate download sources.
If you want to proceed and need more help, please write back.