Simple because you know what you want to accomplish, but complicated because it has to be done with so few words. With some practice you should have no problem getting lots of inquiries from your ads. How great you or your company are, or how great your product is. The only thing the reader cares about is himself. Almost all weekly and monthly publication will charge for each word including your company name and address.
Most daily newspapers have a per line rate.
Since just the address can take up from 6-10 words here are some ways you can save money. The following ad has 23 words. Easy to do. This ad has 21 words. Easy to do.