Hi @dhabagira
Here is the [https://dl.dell.com/manuals/all-products/esuprt_laptop/esuprt_vostro_notebook/vostro-3350_owner's%20manual_en-us.pdf|manual] for the laptop.
Go to p.19 to view the procedure to remove/replace the memory.
Here are the memory specifications for the laptop:
Two SODIMM slots
Each memory slot supports 1 GB, 2 GB, and 4 GB modules
Memory type DDR3 SDRAM 1333 MHz i.e. PC3 10600
Minimum memory 2 GB, Maximum memory 8 GB i.e. 2 x 4GB
You need a 64-bit OS to recognize >4GB of memory e.g. Win 7 64 bit or Win 10 64-bit and not Win 7 32-bit etc.