The Seagulls first match in the top flight since 1983 ended in a 2-0 defeat against Manchester City at The Amex on Saturday, with both the visitors' goals coming in the final 20 minutes after costly defensive errors.
Individual mistakes also cost Chris Hughton's men during their final pre-season match, a 3-2 defeat to Atletico Madrid last week, and Australia international Ryan knows they must quickly sort out their issues, otherwise they could face a tough top-flight campaign.
"We need to stick together for our defensive work," he told the club's website. "In the last two games, the goals we have conceded have come down to our errors and not down to great play from the opposition.
"Fingers crossed we can rectify that going forward, but we are still finding our structure."
Ryan is convinced Brighton will soon adapt to the rigours of the Premier League, particularly as they get used to playing against teams of City's quality.
He added: "This team has not played anyone big in the last couple of seasons, so there’s not a lot of experience playing against these sides."
Brighton will be hoping to pick up their first points as a Premier League side when they take on Leicester at the King Power Stadium next Saturday and punters may choose to use their free bet to back the Seagulls to win.