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Some issues in your project at given time are synchronized . You need to be aware about sync criteria, for example if issue met JQL defined in Contract (IssueSYNC 1.x.x) configuration or what triggers update remote issue.
First issue need to be created in the remote JIRA. Only then fields, workflows and others will be synchronized. See Triggers, Workflow Synchronization, Attachment for moreautomatically (often just after your own local issue creation, defined by Triggers) or manually by hitting Create Remote Button (also see below). 
Fields, comments, attachments, workflows and other will be synchronized if remote issue (see below) does exist.

Remote Issue Panel

Once your issue is replicated in remote JIRA you will see remote issue key . You also see a Contract (IssueSYNC 1.x.x) listed just under a Context name that defines conditions for your synchronization. In that case Contract

Example:
Context name is 'Story' and remote issue key SC-15.

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You can also see  indicator that tells you there are some changes not synchronized yet. You need to wait (often) a bit in rare cases it takes longer than few minutes to reflect changes in remote JIRA and make indicator disappear.  
Note! If you have access (credentials) to remote JIRA you can click remote issue key to be forwarded to , it will redirect you to remote issue in remote JIRA instance. Image Removed

In some scenarios/configurations remote issue may be created by pressing Create Remote button. You will not see this button in case remote issue already exists (so you are not able to create duplicates that way).

See Create Remote Action

Synchronization History

Synchronization History tab allows you to see when and what type of data was exchanged with between local and remote issue in a simple form.

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There are more options included depending on synchronization status (see Retry).

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You can search over remote issue key using JQL. You need to setup Synchronized Issues View custom field first.

Synchronization Panel

Synchronization panel is advanced diagnostic panel that gives you insight into details of given ticket synchronization. You can Flush changes faster, see Contract settingsContext setup, outgoing and incoming messages by type and status, browse logs and errors.

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