Hello Gautham,
you can create your company's ESS, and can upload your companies logo in the ESS screen. for that what you have to do is simple.
follow these steps
1. Go to; C: >Program Files (x86) >Lenvica HRMS >Web >img
2. Change the default logo to your logo.png. So that the same thing will reflect in the ESS
point to be noted image size- 260×90