Use scissors to make series of slits of 5 cm long in the side of the liner so that the trailing plants that you will use for this side of the basket are one or two levels below the basket rim, so when they will grow will fill out the space and cover the wire frame of the basket.
Part-fill with the compost mixture, in which you can add some water-retaining granules in order to help you with the maintenance of the basket, allowing you to water it less often. Firm the compost and start planting the first row of plants that are going to be insert in the slits that you have made on the side of the liner.
To protect the plants, wrap each one of them in strips of plastic, forming a cone over the stems and leaves. Insert each plant cone into slits from within the basket and when the plant is in position, carefully remove the cone. Plant all the side plants in the slits, tease out the root balls and add compost until the basket is filled within 5 cm of the rim.
Plant the second layer of plants around the edges of the basket letting them to spill over. Add more compost and finish the planting by adding the central plant or plants in the middle of the basket. Top of with compost so that the final surface is 2.5 cm below the basket rim. Water well and top up extra compost where any sunken areas may appear.
Allow the plants to establish in a sheltered place before hanging the basket in its position. Keep the compost moist but not overwatered.