Buy charts (Skip this step if you only need to update charts with valid subscriptions)
Initialize a microSD card
Download your charts using LightHouse Manager (or download updates of existing charts)
Download and install the LightHouse Manager software (download for Windows 7 / 8.1 / 10 here | download for Mac OSX here), launch it and follow the prompts to download your chart to your initialized microSD card. More info.
Use your charts!
Insert the card with the downloaded charts into your compatible Raymarine chartplotter. In the chart screen, select Menu > Presentation > Chart Selection. This will show the list of available charts. Select your downloaded chart to open it.
Need more help? Detailed Instructions here.