I am not sure how to say in English the following sentences exactly? Please help me!!!!!!!
I wish to say thank you to all of you for your friendship and what you did during my tenure with this office, and the wonderful present you gave me will serve as lasting memory of the happy times I shared with all ofy ou.
My suggestions:
I wish to say thank you for your friendship and assistance / help during my time in this office. The wonderful present you have given me will serve as a lasting reminder of the happy times I shared with all of you.