Congratulations for getting your LULU First Slave Tatt. If you have a Mesh Body (e.g. Maitreya, SLink etc.) a regular Tattoo will not work. You need Omega Advanced Appliers.

These are the steps:

1) Buy an Omega Applier System Kit suitable for your Body.

    e.g. 

    For a Maitreya body, go to https://marketplace.secondlife.com/p/Omega-System-Kit-Maitreya/6709966

    For a SLink body, go to https://marketplace.secondlife.com/p/Omega-System-Kit-Slink/7671377

    For others, just look around the rest of the store https://marketplace.secondlife.com/stores/133475

2) Wear the Omega Applier Relay HUD in the kit.

3) Wear your LULU First Slave (Omega Applier) HUD and click it.

A menu will come up asking which layer you wish to apply to. Just select Tattoo.