Should I use Indexes on mySql table?
I have a table in mysql, in which searching, insertion, deletion and updation is done quite frequently and I have read that indexes affection insertion and updation performance. so should I use Indexes for faster searches? 


Yes, there is an overhead in having indexes when changing data.  As well as updating the base data table, the DBMS also has to update the index structures as well.  That overhead, however, is small.  Remember the all changes are [quickly] written to memory first and only flushed [slowly] to disk some time later. 

Indexes exist primarily to improve query performance and can do so by Orders of Magnitude.  Imagine retrieving a single record by its unique ID: 


If that field is indexed then the DBMS can quickly skip through the index [blocks], then "hop" across to the data page to get any additional fields.  
Without the index the DBMS has to scan each and every record in the table.  If that table has millions of records, that's going to be really, really slow.  Even with a "limit 1" clause, telling the DBMS to stop at the first match, you'll still be reading half the table, on average. 


So Indexes are a trade-off.  They can make you [huge] gains on the querying front, while making [small] losses on the update front.  The only person who can definitively tell you whether it's worth your while to index your fields is you, based on your database and your Application.  Test that Application with and without indexes and compare the results.  

That said, I strongly suspect you'll come back in favour of using them :-)