How can I get legal assistance to ensure that I am not infringing on patents of a company that patented a similar idea?

You need to hire a patent attorney to engage in a "freedom to operate" opinion. That opinion will evaluate ALL current patents and published applications (not just the one that you found) to determine if your product would infringe anyone else's patent rights.

Do not hire a patent attorney to solely conduct an "infringement analysis" that considers whether your product infringes the one patent that you located. That type of opinion does not go far enough for your needs.

As a practical matter, your consultation with your patent attorney may assist you, if necessary, in re-developing your product with "design around" features so that it will not infringe one or more or the patents that are located by your patent attorney. So the opinion work that you're buying does double duty.

Inventors who work in technologies for which patents are available cannot escape hiring a patent attorney to help them navigate through the patent landscape in which they're traveling.

Mr. Ballard's answer above is very good. Your patent attorney is going to be able to help you identify all of the closest related prior art (not just the patents you've seen) and, as Mr. Ballard has suggested, help you identify design elements of your product that prevent you from infringing others' patents. The addition I wanted to make for anyone else interested in the answer to your question is that the best time for this analysis (freedom to operate / freedom to practice) is prior to making any significant R&D investments (time and/or money) in developing your invention to keep you from getting too far into the project before seeing what potential roadblocks exist. As with nearly all aspects of patent law, the sooner you include a patent attorney that has your best interests in mind in the strategic planning, the more efficient you will be able to be with your development investments.

One other point is that there is a big difference between what is described in a patent and what is claimed. The claims are the enumerated paragraphs at the end of the patent that define the legal scope of the invention. When comparing your product to a patent, for infringement purposes, you should focus on the claims and compare the wording of the claims to your product. To infringe a patent, your product must be covered by only one claim, so be careful. Of course, words can be interpreted in different ways, and you should generally read the claims in such a way to give the broadest reasonable interpretation of the words that are presented. However, in some cases, words or "limitations" in the claims can be construed narrowly, based on arguments made to the patent office during prosecution, explicit statements that narrowly define words, or amendments made during the prosecution of the application turned patent.

So, in summary, while the specification of the patent (the description before the enumerated claims) may be very, very broad, only the claims are important for infringement - and if there is a limitation present in all of the claims that your product does not have, then you do not infringe.