I'm new in the QA field and the company i'm working for needs me to write tests scripts for their online search engine. Also for their data migration and also for their UAT. Could any one please help me with this. Help would be greatly appreciated.
That's a very tall order, when you're brand-new and don't know how to start.
For the online search engine, read their specifications and start by making a list of what needs to be tested. If there are no specifications, but they already have some form of system available for you to work from, look at their system and write down a list of what needs to be tested. These are your test requirements.
Get a copy of a standard test case document and flesh out your test requirements, as time is available.
For the data migration, it depends on what this involves. You might be able to use test cases, and you might need something more like a mapping document (old data/new data).
You are not really the appropriate person to have writing UAT tests. This should be done by the end user. The way in which UAT differs from standard QA/QC testing is that the user should be validating that the system supports their workflow and that they can use the system effectively.
Many "new" QA analysts like Ed Kit's book, "Testing in the Real World", because it has examples and exercises. You might want to try it.