WMD
You have just asked one of the most simple or complicated questions one can ask. There are three basic views to what your asking. I will try and keep it simple, but will give you a little tiny bit of theology.. There have been books the sizes of Bibles written on the works of the Holy Spirit.
First. When A person beomes a Christian,at that moment the Holy Spirit enters that person. Some people they are filled to the brim, but it is rare. Another gift or gifts aside from the Holy Spirit and Eternal life that one recieves are spiritual Gifts. Speaking in tongues is not evidence of being filled with the Holy spirit. Not all do and most never recieve that Gift. I my self do not have that gift and I have been filled with the Holy Spirit.
One view and the bible does teach is a second work of Grace. This is taught by Wesly or Armenianism and basically what it means is that at 1 time and 1 time only you will be filled to capacity with the Holy Spirit and from that moment on your walk will have ups and downs, peaks and valleys as is the Christian walk.
Another view is that a person is never trully filled with the Holy Spirit but instead is gradually filled with its peaks and valleys and this is what Calvin taught. That one becomes filled through the justification process which is the rest of your natural life. This view also Holds that nobody is trully saved until they are dead.At that point ones becomes perfect.
Both those views are taught by the bible and there is truth in both those doctrines.
As for me. This is what I believe and The bible teaches this as well. Infact its practiced through the book of ACTS.
Have a spirit filled believer or believers lay hands and pray for you, anoint you with oil, and ask the Holy spirit to fill you. This is what was done to me and what i Have done for others. Now this also is not a one time deal. Just like a car runs out of fuel, so do we. In order to be constantly being filled with the Holy Spirit ( The bible teaches to be, being filled) One must continue to follow after God, read his Bible, Pray, Worship, fellowship and partake in communion.. This is by no means a complete list but just a partial list.
If you have not been water baptized, then I would do that and while your getting dunked simply Ask the Holy Spirit to fill you.
Read Romans Chapter 4 through Romans Chapter 8 and pray while you read and study those scriptures on Justification. Ask the Holy spirit to inetrpret these. Your life will for ever be changed.
If you have any questions on Romans please ask. There are many good teachers on this forum who can help you with this.
You can ask Solo, Vic, Atonement, Golfjack, Lewis and there are more but these are the ones who come to mind right of the bat. These are people who I know have thier theology right. I say this because there are many who don't.
Blessings,
Jg