So, I bought an orchid.

I bought an orchid - a scruffy little one with no spike, blossoms, yet. I’ve put it in a new pot with some moss, but left the original root ball alone. I want to shock it as little as possible.

I want to keep it in my office, where there is no natural sunlight. There is diffuse overhead light, and two small desk lights.

How do I keep it alive until it grows large enough to blossom?

Good luck with the orchid…they can be addictive and you may end up with several. Orchids like indirect light for the most part, but AFAIK it doesn’t have to be natural light (our main orchid supplier where I work grows his in caves) so you may be able to get it to bloom in an office. Probably the wildest thing going around right now is the fad of the “just add ice” orchids. Don’t water your orchid with ice! Water it in your sink once per week (more if your climate makes your orchids very dry) with lukewarm water and it will be happy–after all, how would you feel in an ice cold bath? After mine bloom, I wait until the stems are dead, cut them off, then re-pot the entire orchid in a slightly larger container. Don’t use soil as your potting medium when you re-pot them. I use chopped up wine corks and the orchids love it! I’ve been somewhat successful at getting them to re-bloom. If you just can’t get yours to flower again, don’t throw it out, but donate it (save the paperwork with the information on the species, etc) to your local botanical garden.

Thank you. Especially for the cork tip.

I really don’t think I have to worry about ending up with several - I’ve killed spider plants and golden pothos. We generally refer to my attempts to raise house plants as ‘compost’.

First thing first, you need to figure out what kind of orchid it is. Phalaenopsis, Dendrobium, Oncidium, and Cattleya are some of the most common kinds grown as houseplants so try googling images of those and see if it looks like any of them. I am a fan of phals myself - I find them the easiest (for some reason, I find african violets much harder to keep alive than Phal orchids).
The different kinds of orchids vary in how much light, water, etc. they like so that’s why it is important to know what kind you have.

Unfortunately I would wager that for just about all of the types of orchids, typical room lights are not going to be enough light for the plant to grow well, much less bloom (many houseplants will survive at low light levels but need higher light to thrive and bloom). You could look into setting up a supplemental artificial light if you really want to keep the orchid in its current location, or otherwise once you’ve figured out what kind of orchid you have you can sit it on a windowsill. In the northern hemisphere, northern windows give the least light, east and west medium amounts of light, and southern windows give the strongest light. A Phal will be content in a North, East, or West window. Many of the others would really prefer a southern exposure or even spending the summer outdoors for more light.
For some more detailed advice about growing orchids there is a forum here: Orchid Forum - GardenWeb

If it’s an epiphytic orchid (and most of the commercially grown ones are) you want the roots to always have sufficient aeration. That’s why chopped bark (or jennmonkye’s wine corks) work well as substrate. You want to water thoroughly but not leave the roots in water…give them time to absorb plenty but make sure they’re taken out of the water and allowed to air dry.

There are non epiphytic orchids? I don’t think I knew that.

Most of the slipper orchids (Paphiopedilum and Cypripedium) are terrestrial, as well as pretty much all of the temperate-zone orchids, are terrestrial.

Ah, are those like lady slipper?

I plan to leave it packed gently in the spanish moss until I drink enough wine and learn enough about it’s watering and light cycle needs to try to inspire it to flower.

My next plant will be a fly trap.

Yes, the paphs and cyps. There are other small terrestrial orchids in temperate zones that aren’t, though, like Orchis, Pogonia and Calypso.